The present invention relates generally to the preparation of flexible printed circuits, and more particularly to the preparation of electronic packages including printed circuits formed upon a flexible substrate wherein a plurality of circuits are maintained in an array during processing utilizing holding tabs for array integrity. The holding tabs form a releasable retention means as a device for temporarily holding an array together for multiple-up processing of the electronic package. The process of the present invention provides a handling advantage in the processing of flexible printed circuits to form electronic packages through the utilization of multiple-up circuit panels while maintaining the work-in-process in a form wherein certain phases of the overall processing operation may be accomplished on a roll-to-roll basis, with other later phases being accomplished on a multiple-circuit panel basis. The panels are formed from severed segments of an elongated web, and include a plurality of individual circuits surrounded by lateral and end portions upon which the web driving bores as well as fiducial targets or features are located.
The arrangement of the present invention provides a significant production advantage in that it eliminates or reduces requirements for a number of circuit-specific tooling devices or objects which are related to individual or specific circuit patterns, thus expediting the assembly and testing operations and while reducing the overall production and processing costs. In the conventional processing of printed circuits, it has been considered normal procedure to utilize material handling tooling which is circuit or part-number specific, with such tooling being utilized during a number of the processing operations including assembly and testing. In accordance with the present invention, however, the flexible printed circuits are processed or fabricated while being held in a multiple-up web or panel form utilizing holding tabs created by intermittent cut-lines delineating the periphery of individual circuits in the web. Accordingly, the process of the present invention makes it possible to expeditiously prepare printed circuits on the basis of utilizing multiple-up webs or panels while at the same time preserving certain processing operations for undertaking on a roll-to-roll basis.
The process includes the fabrication of a circuit array utilizing fiducial points disposed outside of or within the individual circuits. Each of the individual circuits in the array includes the presence of exposed component mounting pads for ultimately receiving and retaining components thereon. Both active and passive components may be utilized in accordance with the technique of the present invention, and the sequence of operations renders it possible to preserve such components for placement only upon pre-tested good circuits.
The process of the present invention also includes the step of forming intermittent cut-lines to partially sever individual circuits within the array while leaving holding tabs to preserve adequate integrity of the array within the web. In other words, the cut-lines are designed to releasably retain individual circuits in place within the array until processing has been more completely carried out or completed. The holding tabs are arranged in such a fashion so as to make it possible to separate individual finished circuits from the array at a later point either by hand-severing or through means of a mechanical separator.